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5.1.4 Authentication Using Both a PSK and an Asymmetric Key

5.1.4 Authentication Using Both a PSK and an Asymmetric Key​

This mode is a straightforward combination of the PSK and authenticated modes. Like the PSK mode, a PSK is provided as input to the key schedule, and like the authenticated mode, authenticated KEM variants are used.

def SetupAuthPSKS(pkR, info, psk, psk_id, skS):
  shared_secret, enc = AuthEncap(pkR, skS)
  return enc, KeyScheduleS(mode_auth_psk, shared_secret, info,
                           psk, psk_id)

def SetupAuthPSKR(enc, skR, info, psk, psk_id, pkS):
  shared_secret = AuthDecap(enc, skR, pkS)
  return KeyScheduleR(mode_auth_psk, shared_secret, info,
                      psk, psk_id)

The PSK MUST have at least 32 bytes of entropy and SHOULD be of length Nh bytes or longer. See Section 9.5 for a more detailed discussion.

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